Window sash balance



7 any 19, 1936. A. LARSON 2,041,645

WINDOW SASH BALANCE Filed March 17, 1954 4 Shets-Sheet 1 Z Fi .2.

l VENTOR A. LARSON 2,1,646

WINDOW SASH BALANCE Filed March 17, 1934 4 Sheets-Sheet 2 INVENTQRATTORN EYS 4 Sheets-Sheet 3 INVENTOR ATTORN A LARSON WINDOW SASH BALANCEFiled March 17, 1954 A. LARSON WINDOW SASH BALANCE Filed March 1'7, 19544 Sheets-Sheet 4 l ENTOR Patented May 19, 1936 WINDOW SASH BALANCE AlgotLarson, New York, N. Y., assignor to Unique Balance Company, New York,N. Y., a corporation of Illinois Application March 17, 1934, Serial No.716,062

3 Claims.

This invention relates to window sash balances of the type of that shownin Letters Patent of the United States No. 1,864,745 dated June 28,1932, in which there is substituted for the usual sash weight and cord aspring balance in which an elongated spiral member, secured at one endto the sash near its bottom, enters within a coiled spring through a nutsecured to the lower end of the spring, the upper end of the springbeing secured to the window frame. When the sash,

whether upper or lower, is lowered from its highest position the springis wound up or placed under increasing tension by the coaction of thespiral member and the nut and when the sash is again raised its movementis assisted by the tension of the spring which, as it unwinds, causesthe nut to rotate and therefore to travel on the spiral member which isheld from rotation. In the application of such sash balances to heavysashes it has been found that the coiled spring which causes the nut torotate and therefore to travel on the fixed spiral member is not alonesufficient to assist the upward movement of the sash to a desirabledegree and it is the object of 25. the present invention to providemeans to supplement the action of such spring. To that end there iscombined with the sash balance as described in said Letters Patent acoiled spring which is stretched longitudinally and therefore 30 placedunder increasing tension in the downward movement of the sash andtherefore returns to the sash, when it is to be raised, the liftingpower ,which is put into it in the downward movement of the sash, thussupplementing the action of the spring the tension of which is developedby winding through the relative longitudinal movement of the nut, andexerting the greatest lifting power when the lifting power exertedthrough the spiral is least.

In the accompanying drawings, in which several embodiments of theinvention are illustrated: Figure 1 is a view in sectional elevation ofa wooden window to which the improved sash bal- 45 ance is applied, thefigure being broken out to save space.

Figure 2 is a view in vertical section on the plane indicated by thebroken line 2-2 of Figure 1, looking in-the direction of the arrows.

50 Figure 3 is a partial detail view in horizontal section on the planeindicated by the broken line 3-3 of Figure 1, looking in the directionof the arrows.

Figure 4 is a detail view in horizontal section 55 showing the chamberfor the reception of the halance as formed partly in the sash and partlyin the jamb. I

Figure 5 is a detail view partly in elevation, partly in verticalsection and partly broken away showing the spiral balance by itself,except that 5 a portion of a window sash is shown at the lower end ofthe balance.

' Figure 6 is a detail view in sectional elevation -on a somewhat largerscale than that of Figure 5, showing particularly the interrelation ofparts 10 at the upper end of the balance.

Figure 7 is a view in horizontal section on the plane indicated by thebroken line '|--'I of Figure 6, looking in the direction of the arrows.

Figure 8 is a detail view in horizontal section 15 of a portion of ametal window to which is applied the embodiment of the inventionillustrated in Figure 9.

Figure 9 is a view in vertical, sectional elevation on the planeindicated by the broken line 20 99 of Figure 8, looking in the directionof the arrows, the figure being broken out to save space.

Figure 10 is a detail view in perspective illustrating particularly theconnection of the balance to the window frame at the upper end of thebalance.

Figure 11 is a detail view in perspective illustrating particularly theconnection of the balance to the sash at the lower end of the balance,as represented in Figure 9. I

Figure 12 is a view similar to Figure 5, but showing a construction inwhich the function of the tube c of Figure 5 is served in part at leastby the supplemental spring and in which such supplemental spring isspecially formed to develop maximum initial tension.

Figure 13 is a detail view in perspective and on a larger scaleillustrating particularly the connection of the balance to the windowframe, as shown in Figure 12.

Figure 14 is a detail view in perspective and on a larger scaleillustrating particularly the connection of the balance to the sash atthe lower end, as represented in Figure 12.

Figure 15 is a partly sectional view on a much enlarged scaleillustrating more clearly the formation of the supplemental spring shownin Figure 12.

Figure 16 is a detail view in horizontal section of a portion of a metalwindow to which is applied the embodiment of the invention illustratedin Figures 12, 13, and 14.

In the embodiment of the invention shown in, Figures 1-7 the frame ofthe window, embodying the head or lintel a, the jamb a with the partingstrip a and the sill a is shown as constructed and arranged in usualmanner, the upper sash b and the lower sash b being arranged to movevertically therein. In Figures 1, 2 and 3 each side rail of each sash isshown as plowed out or grooved, as at b to receive the spring balance tobe described, while in Figure 4 the chamber or recess to receive thebalance is shown, as at b as formed partly in the sash and partly in thejamb. It will be understood that a balance is provided at each side ofeach sash. Each such balance, as shown in these figures, comprises atube c which receives within it a coiled spring d in the nature of ashade-roller spring. At its upper end the spring d is secured to a,sleeve member (1 which is mounted within the tube 0 at its upper end andreceives internally a nut d consisting of two spaced members, forcooperation with a graduated, ribbon-like spiral member e which issecured at its upper end, as by a pin e to a fixture ,f, which in turnis secured to the window frame at its top, as by a pin F. The lower endof the spring d is, in this illustrated embodiment of the invention,secured to one member d of a clutch. The other member d of the clutchengages the lower end of the tube 0 through lugs d thereby permittingthe clutch members to be disengaged, the spring to be wound up to adjustthe tension and the parts to be reengaged. Secured to the lower end ofthe tube is a bracket 0 for engagement with the sash frame, as shown inFigures 1 and 5. As the window sash is lowered the tension of the springd, through the cooperation of the nut and the spiral, is increasedsomewhat and when the sash is lowered the power thus stored in thespring acts, through the rotation of the nut and the co- ---operation ofthe nut with the spiral, to assist in the upward movement of the sash.The assistance so afforded may be all that is desirable for lightsashes, but it has been found to be insuflicient when the balance isapplied to a heavy sash. For the purpose of supplementing the action ofthe spring 11 in cooperating in the upward movement of the sash whileretaining the advantages in the cooperation of the nut and spiral thereis provided an extensible spring g which is secured at its upper endtothe fixture j and therefore to the window frame at its top and issecured at its lower end, as at c to the lower end of the tube 0 andtherefore to the sash. When the sash is lowered the spring g isextended, as shown in Figure 1 and at the left hand in Figure 2, and thepower so stored in the spring is available to cooperate in the upwardmovement of the sash when it is to be started from a condition of restand at a time when the torsion spring d, acting through the nut andspiral, has the least effect in the raising of the sash. When the sashis in or near its lowest position the spiral, by reason of the longpitch of the part then in engagement with the nut, exerts practically noforce, while the supplemental spring 9, being then stretched, exerts itsmaximum force and takes practically the entire load.

In the application of the invention to metal windows, as illustrated inFigures 8-11, each balance may comprise as before the tube c, the spring(1, the spiral e and the fixture 1, but instead of being placed directlybetween the sash and the jamb, it is placed within a chamber it formedat the outer or inner side of the hollow metal frame or hanging stile has shown in Figures 8, 9 and 10. The fixture f is supported at the headof the window frame by a bracket f which is suitably formed to receivethe supporting pin f, the bracket being slotted, as at f, to permit theintroduction of the pin f and being recessed, as at P, to form seats forthe pin. At its lower end the tube 0 receives a collar 0 which, as shownin Figures 8, 9 and 11, has an arm 0* formed to interlock with a bracket0 extended from the sash b or b as the case may be. As before, thespiral e is secured at its upper end to the window frame at its topthrough the medium of the fixture to which the spring g is also securedat its upper end, the spring g being secured at its lower end to thesash through the medium of the tube 0, the collar 0 and the bracket 0the arm 0 and the bracket 0 being slotted so as to permit disengagementfor the purpose of regulating the tension of the springs. The tube 0 aswill be understood, is provided at its upper end with a nut, as at (F.

When the weight of the sash is considerable it is particularly desirablethat the initial tension of the supplemental spring shall beconsiderable also in order that the spring may be immediately effectivein cooperating in the upward movement of the sash, even when the sashhas been lowered but little. In the practical development of theinvention it has been found that such maximum initial tension can besecured best by forming the supplemental spring 9 as shown in Figure 12and in much enlarged detail in Figure 15. In this spring the wire 9through its effective length is rectangular in cross-section and iscanted and disposed so that each turn of the coil partly overlaps andlies upon the turn next below it. The supplemental'spring thus not onlydevelops high tension when initially stretched, but it also offers suchresistance to lateral deflection that for some uses it fulfillssufficiently the function of the tube 0 in restraining lateraldeflection of the spring d. A balance, comprising such a spring g anddispensing with a separate tube, may be applied to a window, as shown inFigures 12, 13, 14 and 16, in which the spiral e is shown as placed withits end of least pitch down and. therefore engaged at its lower end inthe highest position of the sash, with the nut d which is carried by asleeve cl secured frictionally at the lower end of the spring d. Thesleeve d is free to rotate and is received, when the sash is in itshighest position, within a sleeve c which may be secured to the sash bat or near its bottom by a bracket 0 As the sash moves down the sleeve dis withdrawn from the sleeve 0" and rotates independently thereof. Inthis construction the spiral e is free at its upper end, but the springd is held at this end from rotation, being frictionally engaged with thesleeve i of a bracket which is engaged with a stud i secured to thewindow frame at or near its top. The spiral e is formed atits lower endwith an eye e for engagement with a suitable tool and with a-projectinglug e adapted to engage, under the infiuence of the tension of thespring d, with a beveled detent 0 formed with the bracket 0 supplementalspring g has a strong frictional engagement at its lower end with thesleeve 0 and therefore with the sash b and a similar engagement at itsupper end with a sleeve 1 carried by a bracket i which has a detachableengagement with the stud f' secured to the window frame at or near itstop. The balance as thus formed may be placed within a chamber h,

formed at the outer or the inner side, as the case may be, of the hollowmetal frame or hanging stile h.

To facilitate understanding of the operation of the invention, as itfinds expression in the several embodiments illustrated and describedherein, it is noted that when the balance is applied to the upper sashof a double hung window, as shown at the right hand in Figure 2, withthe spiral placed with its end of steep pitch uppermost, neither thespring d nor the spring g is under material tension and the nut d iscarried by the tube c at its upper end; when the sash is moved downward,to open the window from the top, the nut 11 is moved downward on thespiral e increasing the tension of the spring d and at the same time thesupplemental spring g is ex-- tended and placed under tension, the forcewhich operate in the upward, closing movement of the sash. On the otherhand, when the balance is applied to the lower sash, as shown at theleft hand in Figure 2, and the sash is then in its lowermost and closedposition, the nut 11 is at or near the upper end of the tube 0, thespring d has been placed under tension by the downward movement of thenuton the spiral, and the supplemental spring 9 has been fully extended.The force thus stored in the springs is therefore ready to assist in theupward movement of the sash from its closed position. What has alreadybeen stated with respect to the application of the balance to the upperand lower sashes, as represented in Figures 1-7, is true also withrespect to the application of the balance to the upper and lower sashesas shown in Figures 8-14. In the embodiment of the invention illustratedin Figures 12-16 the spiral is shown as placed with its sharply pitchedportion lowermost and in this instance, in the construction shown, thenut d? is at or near-the lower end of the tube in engagement with thesharply pitched portion of the spiral, this arrangement being applicableto the upper sash.

In the old construction shown in applicant's prior Patents No.1,864,745, June 28, 1932, and No. 1,926,951, September 12, 1933, inwhich a torsion spring alone is relied upon to assist the operator inthe lifting of the window, the formation of the spiral member is such(the pitch of the spiral increasing slowly toward the lower end) that asthe lower sash, for example, is moved 'downward and reaches its lowestposition the torsion spring is most fully wound up. Then as the sash israised and the torsion spring unwinds the loss of lifting power in thetorsion spring as it unwinds is compensated by the form of the spiral,the lifting power of which increases by reason of the reduced pitch ofthe spiral.

The construction above referred to works satisfactorily in applicationto sashes which are not too heavy, but when the torsion spring alone isapplied to a very heavy sash it is inadequate and it is necessarytherefore to supplement the torsion spring by the provision of a tensionspring. The lifting power of the tension spring is maximum when thetension spring is fully extended, that is, when the lower sash is allthe way down. As the sash is raised and the tension spring is shortenedits lifting power becomes less.

As the liftingpower of the tension spring obvlously decreases during theupward movement is so stored in the springs being returned to conut isthen engaged. l0

To compensate for the thus reduced power of the torsion spring, due tothe pitch of the spiral, the tension spring must have high initialtension to compensate for the decreased lifting power of the torsionspring and because the lifting power 15 of the torsion spring increasesas the sash moves upward, by reason of the progressively lower pitch ofthe spiral, the lifting power of the tension spring may increase moreslowly.

It will be understood that details of construction, particularly asinvolved in the application of the balance to the window, may be variedto suit different conditions of use and that, except as pointed out inthe accompanying claims the invention is not restricted to theparticular constructions shown and described herein.

I claim as my invention:

1. A sash balance for a window comprising a coiled torsion spring, a nutcarried by the spring,

a spiral member of rapidly increasing pitch toward the lower end adaptedto be connected at one end to the window frame and cooperating with thenut to effect the storing of power in the torsion spring as the sash islowered and the return of power to the sash to assist in the raising ofthe sash, and an extensible coiled spring of high initial tension andslow increase of tension as extended adapted to be connected at one endto the window frame and at the other end to the sash in which power isstored in the lowering of the sash and from which the stored power isreturned to the sash to cooperate with the torsion spring, the torsionspring acting as an equalizer of the extensible coiled spring, and thetwo springs acting together as one element.

2. A sash balance for a window comprising a coiled torsion spring, a nutcarried by the spring,

a spiral member of rapidly increasing pitch toward the lower end adaptedto be connected at one end to the window frame and cooperating with thenut to effect the storing of power in the torsion spring as the sash islowered and the return of power to the sash to assist in the raising ofthe sash, a tube enclosing the spiral member and the spring andconnected at one end to the spring and adapted to be connected at theother end to the sash, and an extensible coiled spring of high initialtension and slow increase of tension as extended surrounding the tubeand adapted to be connected at its upper end to the window frame and atits lower end to the sash in which power is stored in the lowering ofthe sash and e from which the stored power is returned to the sash tocooperate with the torsion spring in the raising of the sash.

3. A sash balance for a window comprising a coiled torsion spring, a nutcarried by the spring, a spiral member of rapidly increasing pitchtoward the lower end adapted to be connected at 70 one end to the windowframe and cooperating with the nut to effect the storing of power in thetorsion spring as the sash is lowered and the return of power to thesash, a tube enclosing the spiral member and the torsion spring and con-7 nected at one end to the torsion spring and adapted to be connected atthe other end to the sash, and an extensible coiled spring of highinitial tension and slow increase of tension as extended independent ofthetorsion spring and the tube and parallel therewith, said extensiblespring being adapted to be connected at its upper end to the windowframe and at its lower end to the sash and in which the power is storedin the lowering of the sash and irom which the stored power is returnedto the sash to cooperate with the torsion spring in the raising of thesash.

ALGOT LARSON.

